Persistent mesh for isolated mobile and temporal networking

Abstract

A structured wireless mesh network is disclosed where a tree-like connection topology is formed. In one embodiment, each node has separate uplink and downlink radios operating on different channels. When a cluster of such nodes becomes isolated as in the case of a mobile mesh application, a node in the cluster according to this invention acts as a root node thus enabling the tree structure to persist, even in isolation. Example methods of joining sub networks are disclosed that guide the joining of mesh networks and channel management. Nodes that may operate in isolation also support a distributed DHCP capability such that IP addresses are assigned to clients even when a connection to a central DHCP server is unavailable.

The invention claimed is: 
     
       1. A structured mesh network capable of isolated operation, comprising:
 at least two structured mesh nodes; 
 wherein each structured mesh node comprises at least a connectivity logic; an uplink radio operating on an uplink frequency and a downlink radio operating on a downlink frequency; wherein the connectivity logic determines whether each structured mesh node connects with an external network or another structured mesh node using its uplink radio and whether client devices or other structured mesh nodes connect to each structured mesh node using said each structured mesh node's downlink radio; 
 wherein the structured mesh network functions in two configurations selected depending on whether a connection to said external network is present—a connected configuration and an isolated configuration; 
 wherein in the connected configuration the structured mesh network includes at least one structured mesh node whose uplink radio comprises a connection to said external network; and 
 wherein in the isolated configuration none of the structured mesh nodes' uplink radio comprises a connection to said external network, and one of the structured mesh nodes acts as an isolated network root node of the isolated configuration and all remaining structured mesh nodes connect to the isolated network root node as isolated root children nodes forming a tree configuration; 
 wherein clients and children nodes of each structured mesh node of the structured mesh network in the isolated configuration retain full connectivity within the structured mesh network when the isolated configuration is in effect; wherein the structured mesh network in the isolated configuration includes the isolated network root node having a local Dynamic Host Configuration Protocol (DHCP) server for the isolated configuration, 
 wherein said DHCP server randomly selects a random address range from which to assign addresses to clients of said DHCP server. 
 
     
     
       2. The structured mesh network of  claim 1  wherein the connectivity logic contained by the structured mesh nodes realigns connections between the structured mesh nodes upon loss of said connection to said external network to form the isolated configuration. 
     
     
       3. The structured mesh network of  claim 2  wherein the connectivity logic contained by the structured mesh nodes designates the structured mesh node which in the connected configuration was connected to the external network as the isolated network root node. 
     
     
       4. The structured mesh network of  claim 2  wherein the connectivity logic contained by the structured mesh nodes designates the structured mesh node which in the connected configuration passed the most traffic as the isolated network root node. 
     
     
       5. The structured mesh network of  claim 2  wherein the connectivity logic contained by the structured mesh nodes selects the isolated network root node such that the resulting network's traffic traverses a minimal number of nodes. 
     
     
       6. The structured mesh network of  claim 2  wherein the connectivity logic contained by the structured mesh nodes selects the isolated network root node such that the isolated network root node is the most proximate to an external network connection point. 
     
     
       7. The structured mesh network of  claim 2  wherein the connectivity logic contained by the structured mesh nodes selects the isolated network root node such that the resulting network's throughput is maximized. 
     
     
       8. The structured mesh network of  claim 2  wherein the connectivity logic contained by the structured mesh nodes selects the isolated network root node such that the resulting network's latency is minimized. 
     
     
       9. The structured mesh network of  claim 1  wherein the connectivity logic contained by the structured mesh nodes realigns connections between the structured mesh nodes upon detection of an external network connection to form the connected configuration. 
     
     
       10. The structured mesh network of  claim 9  wherein solely the isolated network root node searches for the external network connection and establishes said external network connection. 
     
     
       11. The structured mesh network of  claim 10  wherein the uplink radio of the isolated network root node is used to connect to the external network. 
     
     
       12. The structured mesh network of  claim 1  wherein a first mesh network in the isolated configuration comprises a first isolated root node and one or more first isolated children nodes and a second mesh network in the isolated configuration comprises a second isolated root node and at least one or more second isolated children nodes and at least one first isolated children node of the first mesh network establishes communication with a second isolated children node of the second mesh network, thereby triggering a realignment due to joining in both networks. 
     
     
       13. The structured mesh network of  claim 12  wherein as part of the realignment due to joining one of the first and second isolated root nodes becomes an isolated network child node wherein the first or second isolated root node of the smaller of the first and second mesh networks becomes the isolated network child node. 
     
     
       14. The structured mesh network of  claim 12  wherein as part of the realignment due to joining one of the first and second isolated root nodes becomes an isolated network child node wherein the selection of the new isolated root node is made on the basis of physical position and direction of travel of the two networks. 
     
     
       15. The structured mesh network of  claim 1  wherein a first mesh network in the isolated configuration comprises a first isolated root node and one or more first isolated children nodes and a second mesh network in the isolated configuration comprises a second isolated root node and at least one or more second isolated children nodes and the first isolated root node of the first mesh network establishes communication with a second isolated child node of the second mesh network, thereby the first isolated root node of the first mesh network becomes another second isolated child node of the second mesh network. 
     
     
       16. The structured mesh network of  claim 15  wherein the uplink radio on the first isolated root node of the first mesh network establishes communication with the second isolated child node of the second mesh network. 
     
     
       17. The structured mesh network of  claim 16  wherein solely the first isolated root node of the first mesh network establishes communication with the second isolated child node of the second mesh network. 
     
     
       18. The structured mesh network of  claim 1  wherein the DHCP server random address range is broadcast by the isolated network root node in a special information packet to other nodes when the isolated network root node is scanning to join said other nodes.